Abstract: The effects of glutamine transaminase (TG) on the mixing properties, stretching properties, rheological properties, microstructure and protein profile of whole wheat dough were investigated using Mixolab, texture analyzer, dynamic rheometer, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and electrophoresis apparatus. The results showed that with increasing the amount of added TG, the water absorption rate of whole wheat dough decreased and the dough development time and dough stability time increased first and then decreased, the peak viscosity increased, the setback decreased, and the tensile strength increased first and then decreased. With increasing TG concentration and reaction time, the elastic modulus (G’) and viscosity modulus (G”) increased, and the tangent of loss angle (tanδ) decreased. However, when the TG concentration was higher than 2.4 U/g and the reaction time was longer than 120 min, excessive protein cross-linking and aggregation took place, accompanied by a decrease in the comprehensive viscoelasticity. The results of SEM and LCSM showed that the addition of TG made dough microstructure more continuous and compact, significantly improving gluten structure. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that TG induced protein cross-linking and aggregation.

Key words: whole wheat dough; glutamine transaminase; mixing characteristics; rheological properties; microstructure